1. Field of the Invention
The present disclosure relates to the treatment of alopecia and/or hair depigmentation. In particular, the disclosed invention relates to the use of PEDF-derived polypeptides for treating alopecia and/or hair depigmentation.
2. Description of Related Art
Alopecia means loss of hair from the head or body, and can be categorized as either cicatricial (scarring) alopecia or non-cicatricial (non-scarring) alopecia. In patients with cicatricial alopecia, the hair follicles would be destroyed and replaced with scar tissues, whereas in patients with non-cicatricial alopecia, there are no such irreversible damages. While not life-threatening, alopecia affects personal appearance, and therefore personal social interactions, self-esteem, and psychological wellbeing.
Non-cicatricial alopecia includes anagen effluvium, telogen effluvium, androgenic alopecia, and alopecia areata, each of which is resulted from a distinct biological defect. Depending on the type of alopecia a subject might be experiencing, its effects on the hair follicles differs accordingly.
Anagen effluvium is generally caused by abrupt cessation of mitotic activity in hair matrix cells of anagen hair follicles. As such, the hair follicles produce either no hair, or narrow defective hair sheaths which are predisposed to fracture and loss. Anagen Effluvium is common in patients underwent chemotherapy or radiotherapy. Generally, hair follicles would resume their original growth cycle once the cause of anagen effluvium ceases to exist. Hence, in most cases, re-growth of hair starts after the treatment ends. However, the color and texture of the newly grown hairs may be different from those of the original hairs.
Telogen effluvium occurs when cycling hair follicles enter the telogen phase of the hair growth cycle prematurely, thereby causing excessive shedding of hair. It may be caused by various stress-related conditions, including imbalanced diet, medications (e.g., beta blockers, calcium channel blockers, antidepressants, and non-steroidal anti-inflammatories, etc.), childbirth, high fevers, major surgery, an over- or under-active thyroid gland, severe infections, severe chronic illness, and severe psychological stress. Generally, hair loss appears 3 to 4 months after the individual had experienced any of the stress incidents; and the lost hair will be replaced within 6 to 12 months.
Androgenic alopecia (also known as male pattern baldness) is the most common type of male hair loss. Androgenic alopecia affects both male and female, although female subjects tend to lose less hair than male subjects. The underlying mechanism for androgenic alopecia is not well understood. However, it is believed that the hypersensitivity of hair follicles against dihydrotestosterone (a derivative of androgen) is associated with the development of androgenic alopecia in men. The hypersensitivity may cause the miniaturization of hair follicles and shorten the anagen period of hair follicle cells, thereby resulting in the formation of the club hair which is eventually shed from the hair follicle.
Currently, there are two drugs proved by the U.S. Food & Drug Administration (FDA) for the treatment of androgenic alopecia: topical minoxidil (brand name: ROGAINE®) and oral finasteride (brand name: Propecia®). Minoxidil is a potassium channel agonist that affects the hair follicles by extending the anagen period of hair follicles, stimulating the telogen-to-anagen transformation, and promoting the follicle size enlargement. Minoxidil is also applicable in the treatment of alopecia areata as well as anagen effluvium caused by chemotherapy. Finasteride is a competitive inhibitor of type II 5-α-reductase, an enzyme that converts testosterone to dihydrotestosterone (DHT). Therefore, finasteride treats androgenic alopecia by blocking the activity of type II 5-α-reductase. Although these two drugs stimulate hair regrowth in some patients, they are only effective during the medication period, and hence, the patients are advised to take the medication continuously. In addition, use of minoxidil or finasteride is occasionally found to be accompanied by a number of side effects. Possible side effects of minoxidil include scalp itching or rash; decreased libido; elevated heart rate; difficulty breathing; weight gain; and hypertrichosis. Possible side effects of finasteride include skin rash; breast enlargement or tenderness; testicular pain; decreased libido; decreased volume of ejaculate; and impotence.
Hair color is the result of pigmentation of the hair. When the supply of the pigment (i.e., melanin) from the melanocytes decreases, the newly grown hair would loss its original color and exhibits a lighter or even white color, a phenomenon generally known as hair depigmentation. Factors that cause hair depigmentation includes at least, aging, stress, disorders (e.g., piebaldism), etc. In addition, hair depigmentation is often found in newly grown hairs of patients whom previously underwent chemotherapy or radiotherapy. To date, there is no medical treatment that is effective in inducing the depigmented hair to regain its former color. Therefore, most people experiencing hair depigmentation have to cope with their appearances or to cover the depigmented hair by dying the hairs or by wearing a wig.
In view of the foregoing, there exists a need in the art for means that effectively treats various types of alopecia and/or hair depigmentation.